Which of the following describes a function of the soleus muscle?

• A. Deceleration of internal rotation of the tibia
• B. Deceleration of calcaneal eversion
• C. Slows down anterior motion of the tibia
• D. All of the above

Answer: (D)

The soleus is a powerful plantarflexor that also helps stabilize the leg during weight-bearing by influencing tibial and hindfoot movements. When the foot is fixed and the body moves over it, the soleus can act eccentrically to slow forward, or anterior, motion of the tibia relative to the foot, helping control the progression of the tibia during stance. Its posterior position and pull on the posterior tibia also contribute to resisting internal rotation of the tibia, since a backward-tending pull counteracts the tibia rotating inward as the body moves. In addition, its attachment to the calcaneus via the Achilles tendon means it helps stabilize the hindfoot and decelerate calcaneal eversion, aiding in maintaining a more neutral subtalar position during stance. Taken together, these roles show the soleus participates in decelerating internal tibial rotation, slowing calcaneal eversion, and limiting anterior tibial motion. Therefore, all of the described functions describe what the soleus does, making that option the best answer.